IPv6 takes one step forward, IPv4 two steps back in 2012

IPv6 rollout is still inefficient with problems ahead, but there is slow progress.

In hindsight, we reached peak IPv4 two years ago. The good news is that IPv6 is doing very well—but not nearly well enough. Is the IPv6 glass 1 percent full or 99 percent empty?

"Hi, I'd like to sign up for Internet service at my new apartment."

"That's great! We have the highest speeds at the best prices, you won't be disappointed. But unfortunately, last week Europe ran out of IPv4 addresses. We still have plenty of IPv6, though."

"IPv6? So I can use that to visit all my favorite websites, use IM and VoIP, download podcasts, and watch videos?"

"Well..."

Luckily, I escaped this conversation when recently signing up for an Internet connection. But if I move again next year or even the year after, I could end up with a faster Internet connection that is less functional, because it will no longer let me connect to every other Internet user. All because we ran out of numbers, which don't even cost anything. Sadly, not having them will cost us a lot of time, money, and effort as some cling to IPv4 and others adopt IPv6—by choice or otherwise—over the next few years.

Where we stand

First, let's look at IPv4. Five Regional Internet Registries (RIRs) give out IP addresses in different parts of the world. APNIC (Asia, the Pacific, and Australia) ran out in April of 2011, and this past September the RIPE NCC (Europe, the Middle East, and the former Soviet Union) did the same. As a result, the number of IPv4 addresses given out this year is about a third of what it was in 2010: only 80 million.

(The statistics are derived from files the five RIRs publish on their FTP sites every day. However, the ARIN numbers didn't look right, so I replaced them with those found here. This also changes the earlier reported totals for previous years.)

So ISPs and other users of IPv4 addresses in the RIPE and especially APNIC regions have to make do with whatever is left in their own pipelines—which typically hold six months' to two years' worth. There's a final block of 1024 addresses, or they have to do some trading.

ARIN (North America) has 45 million addresses left and gave out 24 million IPv4 addresses this year. So barring unforeseen events, ARIN will be in a situation similar to those of APNIC and the RIPE NCC in the first half of 2014. LACNIC (Latin America and the Caribbean) also has about a year and change until IPv4 addresses run out, while AFRINIC (Africa) has enough for several more years.

Back in 1994, Microsoft's Christian Huitema looked into networks running out of address space, coming up with an "HD ratio." This is the logarithm of the number of systems connected to the network divided by the logarithm of the number of possible addresses. Experience with several different networks showed that an HD ratio of up to 80 percent was reasonable, 85 percent painful, 86 percent extremely painful, and 87 percent the practical maximum.

According to the ISC Domain Survey, there were 909 million systems present in the Domain Name System (DNS) as of July 2012 (resulting in an HD ratio of 93 percent). Obviously, that is well beyond that practical maximum. In this sense, IPv4 is like a tube of toothpaste that's almost empty: every day, if you squeeze hard enough, a little more will come out. But at some point it's easier to just buy a new one.

Now, with IPv4 in decline, surely IPv6 must be ready to pick up the slack? Yes and no. Yes, IPv6 is doing incredibly well compared to even one or two years ago, but... it's not enough.

IPv6 refresher

IP addresses are 32 bits in size, which means there can be some four billion of them. In the early 1990s, the Internet Engineering Task Force (IETF) realized the Internet was growing toward a size that requires more than four billion addresses. Increasing the size of IP addresses required modifications to the layout of IP packets, which meant that all systems that handle IP packets—in other words, everything connected to the Internet—must be upgraded. To be on the safe side, the new system uses an address length of no less than 128 bits, allowing a mind-boggling number of addresses:

340,282,366,920,938,463,463,374,607,431,768,211,456

For unknown reasons, the existing Internet Protocol has version number four. Five was already taken by something else, so the new version got six; hence IPv4 and IPv6. In addition to the larger addresses, IPv6 differs from IPv4 in a number of aspects, so the IPv4 ways of doing things don't always translate one-to-one. But IPv6 is still IP, and it can fulfill the same functions as IPv4. Just on a much larger scale.

IPv6 by the end of 2012: 1 percent full or 99 percent empty?

2012 was a good year for IPv6. Netapp's Lars Eggert has been measuring how many of the top 500 websites have IPv6 enabled. After last year's World IPv6 Day and this year's World IPv6 Launch, we're now at around 10 percent for the top 500 sites in Finland, Germany, India, Japan, South Korea, the UK, and the US. China is lagging behind at 4.8 percent. And of the worldwide top 500 sites, 22.4 percent have an IPv6 address in the DNS, up from eight percent a year ago. However, of the Alexa top one million websites, only five percent have an IPv6 address in the DNS.

According to Google's measurements (Flash required), currently about one percent of its users is able to reach those IPv6-enabled websites over IPv6, up from 0.4 percent a year ago and 0.2 percent two years ago. So the rate at which Google's users are taking up IPv6 has increased from a factor two in 2011 to a factor 2.5 in 2012. If we can stick with that factor 2.5, the entire Internet will have IPv6 by the end of 2017. Of course, these types of growth tend to slow down as they approach 100 percent.

More evidence that IPv6 is taking off can be found in a paper on measuring the deployment of IPv6. Researchers at the Cooperative Association for Internet Data Analysis (CAIDA) observe that after years of linear growth, IPv6 deployment across the autonomous systems (mostly ISP networks) that make up the Internet started to go up along an exponential curve around 2008. The growth of IPv4 autonomous systems, on the other hand, had been exponential until about a decade ago. It's linear since. Note the slightly different scales in the figure, though: 40,000 IPv4 ASes versus 4500 IPv6 ASes.

Last but not least, there are actual IPv6 traffic statistics. Akamai's IPv6 statistics show the content network has 0.8 percent IPv6 hits in North America, 0.3 percent in Europe, and less than 0.1 percent elsewhere. The 0.3 percent number is similar to the amount of IPv6 traffic at two of Europe's big Internet Exchanges: AMS-IX in Amsterdam and DE-CIX in Frankfurt. AMS-IX IPv6 traffic has always been relatively high, but DE-CIX IPv6 traffic has increased from 1 to 5 Gbps in the past twelve months.

For unknown reasons, the existing Internet Protocol has version number four.

The IP defined in RFC 791 was the first widely-used version of the Internet Protocol. RFC mean Request for Comments is a memorandum published by the Internet Engineering Task Force (IETF) describing methods, behaviors, research, or innovations applicable to the working of the Internet and Internet-connected systems.

Interestingly, however, it is not version 1 of IP but version 4! This would of course imply that there were earlier versions of the protocol at one point, but there really weren't. As I mentioned above, IP was created when its functions were split out from an early version of TCP that combined both TCP and IP functions. TCP evolved through three earlier versions, and was split into TCP and IP for version 4. That version number was applied to both TCP and IP for consistency. Even though the name seems to imply that it's the fourth iteration of the key Internet Protocol, version 4 of IP was the first that was widely used in modern TCP/IP. Source

With IPv6 we have enough addresses to give each star in the observable universe an address.

Funny here I am in the backwater called Australia and my ISP has given me IPv6 and I've been running it for nearly two years. Of course, as it should be, I never notice it one way or t'other, but I feel like I have extra brownie points whenever I see an article such as this.Mind you Internode was the first to offer IPv6 in Oz and they are relatively small (or were when the beta was put in place) but it just goes to show what a technological company can doif it tries a bit.

Meanwhile, almost no consumer-grade hardware manufacturer says anything at all about IPv6 compatibility. I had a Linksys business class gateway that supported dual stack, but it was so slow (moving IPv4 packets), that I swapped it out for a Netgear that has 0 support for IPv6, but actually performs well.

So we'd be in good shape if we had been five years further along in IPv6 deployment

No, we'd be in better shape if the people who created IPv4 hadn't been so shortsighted and thought 32bit addressing was enough.

If you think of when these protocols were first invented (around the time of DARPANet in the 60's and 70's, I believe), four billion seemed like more than enough if you think about world population at the time and the fact that even basic personal computers didn't even exist yet, let alone mobile devices. Furthermore, think about the technology back then. A 32-bit address space was significantly expensive in terms of the cost of technology. More than likely, they couldn't even have handled a 128-bit address space then.

So we'd be in good shape if we had been five years further along in IPv6 deployment

No, we'd be in better shape if the people who created IPv4 hadn't been so shortsighted and thought 32bit addressing was enough.

When it was originally created, 4 billion addresses was way, way, way, way more than they ever expected to need.

Seriously. IPv4 was developed when the concept of a computer in the home was still abstract, or at best a hobbyist's toy. A worldwide rollout of computers of various sorts, to the point that there would be many in a single household, or even many for a single person was essentially unthinkable.

When your extremely optimistic estimate is a few hundred million devices, billions of addresses seem like plenty.

Also, hardware was much more limited three decades ago, and IPv4 had to be lightweight enough for computers of the day to handle it.

So we'd be in good shape if we had been five years further along in IPv6 deployment

No, we'd be in better shape if the people who created IPv4 hadn't been so shortsighted and thought 32bit addressing was enough.

If you think of when these protocols were first invented (around the time of DARPANet in the 60's and 70's, I believe), four billion seemed like more than enough if you think about world population at the time and the fact that even basic personal computers didn't even exist yet, let alone mobile devices. Furthermore, think about the technology back then. A 32-bit address space was significantly expensive in terms of the cost of technology. More than likely, they couldn't even have handled a 128-bit address space then.

So we'd be in good shape if we had been five years further along in IPv6 deployment

No, we'd be in better shape if the people who created IPv4 hadn't been so shortsighted and thought 32bit addressing was enough.

If you think of when these protocols were first invented (around the time of DARPANet in the 60's and 70's, I believe), four billion seemed like more than enough if you think about world population at the time and the fact that even basic personal computers didn't even exist yet, let alone mobile devices. Furthermore, think about the technology back then. A 32-bit address space was significantly expensive in terms of the cost of technology. More than likely, they couldn't even have handled a 128-bit address space then.

IPv4 was actually finalized in RFC form in 1981.

Ah okay, thanks for the info. I wasn't exactly sure when the standard was formalized but I figured it had to have been shortly after the DARPANet era. I wonder when the 32-bit address space actually became part of it though? Does anybody know if that has been the case since TCP and IP were a single protocol in versions 1-3?

So we'd be in good shape if we had been five years further along in IPv6 deployment

No, we'd be in better shape if the people who created IPv4 hadn't been so shortsighted and thought 32bit addressing was enough.

If you think of when these protocols were first invented (around the time of DARPANet in the 60's and 70's, I believe), four billion seemed like more than enough if you think about world population at the time and the fact that even basic personal computers didn't even exist yet, let alone mobile devices. Furthermore, think about the technology back then. A 32-bit address space was significantly expensive in terms of the cost of technology. More than likely, they couldn't even have handled a 128-bit address space then.

IPv4 was actually finalized in RFC form in 1981.

128-bit addresses could certainly be managed by then, but I can imagine it would have been considered very costly for no gain at all (consider this would need to run on cheap, rubbish hardware - routers - more than on PCs). And really, who in 1981 would have predicted 4 billion addresses would be remotely limiting? Very few people start out making something considering what limitations they'll run in to if everyone (or nearly everyone) on the planet starts using it.

Their plan includes these deadlines, among others:- Upgrade public/external facing servers and services to operationally use native IPv6 by the end of FY 2012- Upgrade internal client applications... to operationally use native IPv6 by the end of FY 2014

So we'd be in good shape if we had been five years further along in IPv6 deployment

No, we'd be in better shape if the people who created IPv4 hadn't been so shortsighted and thought 32bit addressing was enough.

Cerf had said that they had 3 options on the table. (If I've got some of this wrong I'm sure somebody will correct me)

32 bitvariable length64 bit or higher

Remember that at the time TCP/IP was NOT thought of being some commercial internet but one designed for the military. During the video webcast that I watched Cerf (talked about it at RIT) had said that they just couldn't imagine the DoD needing more than 4 billion addresses.

Variable length gave the engineers a heart attack as the state of the art at the time simply could not handle that processor wise. They simply couldn't justify the added cost in designing, engineering and producing beefier hardware to accommodate a larger space when nobody and I mean NOBODY thought that 32 bit would run out for DoD's use.

So cut the guy some slack. He's often said he regrets that one decision and has been trying to fix it ever since.

About the 32-bit issue: around 1981 only fairly big systems were connected to the internet, and those could probably have supported 48- or 64-bit addresses without too much trouble. Remember that IPX, which was popular in the 1980s and worked pretty well on the predominantly 16-bit PCs of the day, has 80-bit addresses.

miffed: I remember someone from the US government/military saying "we expect the commercial internet to be on IPv6 in five years. It's going to take us longer, so we're starting now to be ready by then", and was ready to single that person out for being too optimistic on both counts, but unfortunately couldn't find a source for that quote so I couldn't include it.

DOCSIS 3.0 and 2.5Gb GPON are both IPv6 native and quickly becoming the standard. I would venture to say more than 50% of the USA is IPv6 native last-mile and the backbone has been IPv6 for almost a decade now.

DOCSIS 3.0 and 2.5Gb GPON are both IPv6 native and quickly becoming the standard. I would venture to say more than 50% of the USA is IPv6 native last-mile and the backbone has been IPv6 for almost a decade now.

Sadly, while the article statement mentioned that you would want to avoid slow software based IPv6 solutions, I'm somewhat at a loss on how you could reliably do so. I'm used to router reviews only measuring IPv4 speeds - IPv6 is simply a matter of pass/fail.

Personally, I'm working around this by simply planning to upgrade as IPv6 becomes more common. I upgraded my modem (now, a Motorola Surfboard 6120) and router (Apple Airport Extreme Gen 4) in preparation for Comcast releasing IPv6 in my area. My initial choices were to simply go with something that Comcast would officially support and then upgrade to something better later. (I figured I'd demote my Airport to becoming an acces point at that time and decide if the router needed to be changed out or not.) I've been dual stack a while now, but I don't think things are good enough to go with the second part of my plan really. IPv6 releases still tend to be slow and I think that Comcast has gotten unstable with the change (and still haven't straightened themselves out yet) so I've kept this setup for a couple years now, and may have it a few years more.

The issue is all of the IPv4 hardware devices out there. It's going to take a decade or more. Basically we have to wait for default IPv6 device support and device turnover.

We are at the point now where adding IPv6 functionality to a device is just a cheap no brainer, so in a few years it will just be a standard feature of every new router, cable modem, phone, picture frame, etc... After that you wait, and wait, and wait, for the old devices to break or become obsolete.

Last but not least, there are actual IPv6 traffic statistics. Akamai's IPv6 statistics show the content network has 0.8 percent IPv6 hits in North America, 0.3 percent in Europe, and less than 0.1 percent elsewhere. The 0.3 percent number is similar to the amount of IPv6 traffic at two of Europe's big Internet Exchanges: AMS-IX in Amsterdam and DE-CIX in Frankfurt. AMS-IX IPv6 traffic has always been relatively high, but DE-CIX IPv6 traffic has increased from 1 to 5 Gbps in the past twelve months.

AMS-IX has not only shown an increase, it has shown a direction. As this real time AMS-IX IPv6 usage graph shows, until June IPv6 traffic was relatively stable (never topping 2Gbps a day), as of last summer's 'IPv6 Launch Day' it doubled within 24 hours. Since then it has gone from being a flat use to a fast and steady increase topping 8Gbps a few days ago.

It appears permanently swichting on IPv6 support by major producers of traffic such as Google, YouTube, Facebook etc. has made all the 'dormant' IPv6 connections people have at home suddenly very active. They watch their videos over IPv6 without probably even realising.

Funny here I am in the backwater called Australia and my ISP has given me IPv6 and I've been running it for nearly two years. Of course, as it should be, I never notice it one way or t'other, but I feel like I have extra brownie points whenever I see an article such as this.Mind you Internode was the first to offer IPv6 in Oz and they are relatively small (or were when the beta was put in place) but it just goes to show what a technological company can doif it tries a bit.

A few months ago I was very surprised to find an IPv6 address on my Gmail activity log. At first I think that I was suspicious that my account been hacked, but after going to some IPv6 test sites I discovered that my work had modified our network to be IPv6 complaint and there was nothing that I had to do.

Story Author wrote:

To be on the safe side, the new system uses an address length of no less than 128 bits, allowing a mind-boggling number of addresses:

340,282,366,920,938,463,463,374,607,431,768,211,456

If mankind lived on 4 billion planets, with 4 billion people on each planet, with each person owning 4 billion devices connected to the internet. Then each device would have 4 billion addresses to choose from.

if these can be capped to a certain limit then the IPv4 address space may have had larger shelf life.upgrading to IPv6 is going to be a major pain especially considering those running end of life / unsupported products.

The IPv6 mandated minimum MTU of 1280 bytes means that systems cannot be configured with a lower MTU than that; however, I can send smaller-byte-sized IPv6 packets through that path without an issue. My MTU can be 9000 and I can still send a 100-byte packet.

The IPv6 mandated minimum MTU of 1280 bytes means that systems cannot be configured with a lower MTU than that; however, I can send smaller-byte-sized IPv6 packets through that path without an issue. My MTU can be 9000 and I can still send a 100-byte packet.

But the software sending data is more likely to support IPv6 than to cap packet sizes manually that way. At best you'll get some packages getting through by accident, while many not getting through, which isn't exactly communicating very well.

Per Comcast's October deployment update, IPv6 has been rolled out to 50% of their network (the half using Arris head-end hardware), and the other half will be deployed by mid-2013. Given their track record with IPv6 so far, this sounds pretty realistic.

So, at this point, that leaves two more bridges for them to cross: customer-interface equipment, and customer-owned equipment. They've been speccing only IPv6-supporting modems for several years now, but I'm sure there are still a lot of IPv4-only modems still in service that they'll have to replace. Then customers will actually have to buy and enable their own equipment with IPv6 support. Individual computers connected directly to the modem will probably be fine (have to get really old and crufty to not have IPv6 support), but the routers will be a very different story.

The IPv6 mandated minimum MTU of 1280 bytes means that systems cannot be configured with a lower MTU than that; however, I can send smaller-byte-sized IPv6 packets through that path without an issue. My MTU can be 9000 and I can still send a 100-byte packet.

Yes, but if your computer has 9000 bytes of data to send, it's going to send it as a single 9000-byte packet. Then, if it gets a message telling it to send smaller packets, it will do so for subsequent packets. But if it's an IPv6 system, it won't go smaller than 1280. If that's still too big, then you have a problem.

Of course if you only have 100 bytes to send in the first place, you're not going to run into any of this. But not too many web pages fit in < 1280 bytes these days.

I'll just mention that there are places like cloudflare.com that allow your site to support IPv6 without changing anything on your stack (for free). I think those types of services will help a lot in getting people moving in the right direction, while everybody continues to play catchup.

The IPv6 mandated minimum MTU of 1280 bytes means that systems cannot be configured with a lower MTU than that; however, I can send smaller-byte-sized IPv6 packets through that path without an issue. My MTU can be 9000 and I can still send a 100-byte packet.

Yes, but if your computer has 9000 bytes of data to send, it's going to send it as a single 9000-byte packet. Then, if it gets a message telling it to send smaller packets, it will do so for subsequent packets. But if it's an IPv6 system, it won't go smaller than 1280. If that's still too big, then you have a problem.

Of course if you only have 100 bytes to send in the first place, you're not going to run into any of this. But not too many web pages fit in < 1280 bytes these days.

Some applications, such as VoIP, would have a major issue if you cannot send packets that are smaller than 1280 bytes. I'm not bundling my voice data into 1280-byte packets because that is the MTU size of my link.

One wonders if there will be the equivalent of a "cash for clunkers" program for routers that don't support IPv6. Maybe like the digital TV rollout?

Probably not. Unlike the radio spectrum, once IPv6 deployment has gotten well along its way, the value of old IPv4 addresses will fall, since their scarcity should start decreasing. More likely, ISPs will start giving out IPv6-only service, at least by default (maybe business-class gets you an IPv4 address), and tell customers who complain to upgrade their hardware.

To be on the safe side, the new system uses an address length of no less than 128 bits, allowing a mind-boggling number of addresses:

340,282,366,920,938,463,463,374,607,431,768,211,456

If mankind lived on 4 billion planets, with 4 billion people on each planet, with each person owning 4 billion devices connected to the internet. Then each device would have 4 billion addresses to choose from.

If we just went strait to 256bit, we could almost have an address per atom in the known Universe. 512bit would allow multi-dimensional universe atomic addressing.

The IPv6 mandated minimum MTU of 1280 bytes means that systems cannot be configured with a lower MTU than that; however, I can send smaller-byte-sized IPv6 packets through that path without an issue. My MTU can be 9000 and I can still send a 100-byte packet.

Yes, but if your computer has 9000 bytes of data to send, it's going to send it as a single 9000-byte packet. Then, if it gets a message telling it to send smaller packets, it will do so for subsequent packets. But if it's an IPv6 system, it won't go smaller than 1280. If that's still too big, then you have a problem.

Of course if you only have 100 bytes to send in the first place, you're not going to run into any of this. But not too many web pages fit in < 1280 bytes these days.

Some applications, such as VoIP, would have a major issue if you cannot send packets that are smaller than 1280 bytes. I'm not bundling my voice data into 1280-byte packets because that is the MTU size of my link.

That's not how MTU works. In fact, if you read the post you just quoted, it says *specifically* that it's not an issue sending for example 100 bytes. It just won't split a 15k chunk of data in to less than 1280-byte chunks for you.

Iljitsch van Beijnum / Iljitsch is a contributing writer at Ars Technica, where he contributes articles about network protocols as well as Apple topics. He is currently finishing his Ph.D work at the telematics department at Universidad Carlos III de Madrid (UC3M) in Spain.